This application is a continuation of application Ser. No. 08/828,903, filed Apr. 2, 1997 and now U.S. Pat. No. 6,667,067, which is a division of application Ser. No. 08/471,065, filed Jun. 6, 1995 and now U.S. Pat. No. 5,686,126.
The present invention relates generally to packages for fresh red meat. Particularly, this invention is directed to the packaging of food products such that the packaged product may be maintained in one condition under certain circumstances and then converted to another condition. Specifically, packages in accordance with the present invention provide for distribution of a packaged product in a low oxygen environment and for introduction of oxygen to the product surface at a supermarket or other retail outlet. Such introduction of oxygen is achieved either by permeation of oxygen through a film in contact with the product surface or through an exchange of atmospheric oxygen with a low oxygen gaseous atmosphere contained around the product.
While a wide variety of food products can be packaged in accordance with the teachings of this invention, it is particularly advantageous in connection with the packaging of fresh red meat such that the meat may be transported in a low oxygen atmosphere, that is, preferably 0.5% O2 or less, most preferably 0.05% O2 or less, and then caused to bloom when it reaches a supermarket by exposure to oxygen.
Historically, large sub-primal cuts of meat have been butchered and packaged in each supermarket. This, however, can be inefficient and result in certain undesirable additional costs. For example, all cuts from a large sub-primal must be sold at once. Instead it would be preferable to permit the meat to be butchered and packaged at a central facility which benefits from economies of scale and thereafter shipped to individual supermarkets such as is done, for example, with many poultry products.
In the past, the goal of central fresh red meat processing has not been achievable because most consumers prefer to buy meat which is reddened in color as a result of exposure to oxygen. However, the meat maintains its reddened color for approximately one to three days and, thereafter, turns a brown color which is undesirable to most consumers.
Therefore, if the meat was butchered and packaged in a gas permeable (hereinafter “permeable”) film, as is typical at retail, at a central location and then shipped to another location for eventual sale, in all likelihood, by the time the package reached the retail outlet the meat would have undergone the transformation to the brown color and would be effectively unsalable. Conversely, if the meat was butchered and packaged at a central location in a gas-impermeable (hereinafter “impermeable”) film, either under vacuum or with vacuum and a low oxygen gas flush, and then shipped to another location for eventual sale, the meat would reach the retail outlet having a purple color which is typical of meat prior to exposure to oxygen. Heretofore, marketing efforts to teach the consumer about the harmlessness of the purple color have proved to be difficult. And, if the gas impermeable film was a component of a conventional package having a tray which is overwrapped or lidded with a film and which contains a low oxygen atmosphere, the impermeable film would have to be removed and replaced with a permeable film in order to allow for bloom of the meat to a bright red color prior to display for the consumer, negating to a large extent the benefits of a central processing facility.
A variety of packages have been developed in an effort to provide a means for transporting meat in a low oxygen environment and for quickly and easily introducing oxygen to the meat at the retail outlet immediately prior to display to the consumer.
One approach to solving this problem has involved the development of peelable films. That is, films have been developed which readily delaminate into permeable and impermeable portions. Such a film is sealed to a support member, such as a tray, which contains the meat product, thereby forming a gas impermeable package for distribution. At the retail outlet, the gas impermeable portions are peeled from the film leaving a permeable film sealed to the tray and, therefore, a gas permeable package which allows the meat to bloom to bright red because of the exchange with atmospheric oxygen.
The peelable film may extend over the contained product and be sealed to the periphery of the tray as a lid or it may be heated and draped over the product under vacuum to form to a vacuum skin package. However, for both types of packages the principal drawback is the relatively low gas transmission rate of the permeable film portion after removal of the impermeable portion. That is, although the permeable portion of the peelable film has a much higher gas transmission rate than that of the entire film prior to delamination, 5,000 to 25,000 cc/m2/24 hrs./atm. at 73° F. a compared to 0 to 50 cc/m2/24 hrs./atm. at 73° F. prior to delamination, it is still too low to effect bloom of the packaged meat in a low oxygen gaseous atmosphere in a short period of time, except in areas of intimate permeable film to meat contact.
Most of the other approaches to achieving the goal of central fresh red meat processing have involved the development of a variety of dual web packages of the type having a permeable film covering the meat product and an impermeable film, which is removed at the retail outlet, covering the permeable film wherein the permeable film and the impermeable film are separate, discreet films.
Examples of these types of packages include dual overwrap packages wherein a permeable film is wrapped around the meat and its support member and an impermeable film is wrapped about the permeable film; dual lid packages which include a permeable lid and an impermeable lid sealed to the periphery of the support member; and packages with a head space which allows for the introduction of a treating gas, typically nitrogen, carbon dioxide or some mixture of the two, between a permeable film adjacent to the meat product and an impermeable upper web. But, as is the case with the peelable films discussed above, each of these dual web packages are limited in their effectiveness by the permeability of the permeable film. Typical gas transmission rates for commercially viable gas permeable films are 5,000 to 25,000 cc/m2/24 hrs./atm. at 73° F. which is too low to effect rapid red meat bloom by exchange of the low oxygen gas and/or gases out and the atmospheric oxygen in.
A further package developed to allow for central fresh red meat processing includes a gas impermeable upper lid with a valve defined in the lid. The package may include a treating gas between the packaged meat and the upper lid during distribution which is withdrawn through the valve and replaced with an oxygen-rich gas. Although a rapid bloom is possible with this system, it has the disadvantages of requiring trained operators at the retail outlet and relatively expensive equipment to exchange each package thus negating the cost savings of a central processing facility. The presence of the valve has the further disadvantage of creating a package appearance which is different from that which consumers are accustomed to seeing for meat packaging. Further, a gas space between the meat product and the impermeable film is required to maintain a bloomed color which yields an underfilled package appearance.
Yet another package developed to allow for central fresh red meat processing provides for an excellent exchange of gases and rapid introduction of oxygen in which an upper impermeable web covers a lower permeable web which includes unsealed areas in the seal of the permeable web to the tray. However, the intermittent sealed and nonsealed areas are formed by an altered sealing head which comprises a series of sealing “fingers” rather than a conventional, continuous sealing surface.
Thus, it is an object of the present invention to provide a package which allows for central processing of fresh red meat with minimal processing required at retail.
It is yet another object of the present invention to provide a package which is similar in appearance to that which consumers are accustomed to seeing for meat packaging.
It is a further object of the present invention to provide a package which allows for rapid bloom of fresh red meat.
It is yet another object of the present invention to provide a package which may be assembled, filled and sealed at a central processing facility on conventional equipment.